St. Monica and The Power of Persistent Prayer by Mike Aquilina and Mark W. Sullivan is an excellent book.
St. Monica has some rough times with St. Augustine. He lived with a concubine and had a child out of what would be considered proper Christian wedlock, he entered into a heretical cult, he even tricked St. Monica and left for Rome by leaving her in a chapel. All through this St. Monica kept praying that things would get better and eventually they did though not in her own time but in God’s time.
Filled with quotes from St. Augustine himself this pray-full read has reflection sections at the end of each chapter. I brings out many topics for consideration about wayward children and family members going through circumstances to St. Augustine and how St. Monica dealt with each situation. From staying close, yet not approving of sin in others to the importance of big talks and why prayers go unanswered.
I highly recommend this great book if you are a pray warrior trying to bring back family members to the Church. St. Monica is the example to beat at this!